Abstract: More and more countries are attaching importance to satellite navigation system，and autonomous navigation is one of the key technologies.Based on 24/3/2 MEO Walker satellite system，this paper analyzes the theory and shortages of PRN ranging，carrier phase ranging along with relevant detection and recovery of cycle-slip.Ambiguity resolution is also introduced.In addition，carrier-phase smoothing PRN ranging and double frequency ambiguity resolution are specifically introduced，which would be meaningful for development of global navigation satellite system.

Key words: autonomous navigation, inter-satellite crosslink, accurate ranging, Pseudo Random Noise code（PRN） ranging, carrier phase ranging

摘要： 卫星导航系统受到越来越多国家的重视，而自主导航无疑是其中的核心技术之一。基于24/3/2构型的MEO Walker星座，分析了伪码测距技术的原理与局限性，在此基础上探讨了载波相位测距技术，以及其中周跳的检测与修复、整周模糊度求解问题，结合星间链路特点提出了两种相应的解决思路，即载波相位平滑伪码测距技术、双频载波相位联合伪码测距技术，对研究具有自主导航功能的全球导航系统具有一定意义。

关键词: 自主导航, 星间链路, 精密测距, 伪码测距, 载波相位测距